Techniques to determine the kinematics of synsedimentary normal faults and implications for fault growth models

Abstract

Normal faults grow via a sympathetic increase in their displacement and length (‘isolated model’) or by rapid establishment of their near-final length prior to significant displacement accumulation (‘constant-length model’). The isolated model has dominated the structural geology literature for >30 years, although some 3D seismic data-based studies support the constant-length model. Because they make different predictions regarding rift development, and earthquake size and recurrence intervals in areas of continental extension, it is critical to test these models with data from natural examples. Here we outline a range of techniques that constrain the kinematics of synsedimentary normal faults and thus test competing fault growth models. We then apply these techniques to three seismically imaged faults, showing that, in general, they grew in accordance with the constant-length model, although periods of relatively minor tip propagation and coeval displacement accumulation, characteristics more consistent with the isolated model, also occurred. We argue that analysis of growth strata represents the best way to test competing fault growth models; most studies utilizing this approach support the constant-length fault model, suggesting it may be more widely applicable than is currently assumed. It is plausible that the very early development of large faults is, however, characterized by the development of faults that, pre-linkage, grow in accordance with the isolated model; we may simply lack the data resolution, especially in the subsurface, to resolve this very early stage of fault growth.

Strike‐slip reactivation of segmented normal faults: Implications for basin structure and fluid flow

“…Over the past several decades, there has been considerable research into the development of normal faults and extensional sedimentary basins (e.g. Anderson, ; Bosworth, ; Cartwright, Trudgill, & Mansfield, ; Childs, Watterson, & Walsh, ; Gibbs, ; Jackson, Bell, Rotevatn, & Tvedt, ; Jackson & Rotevatn, ; Rotevatn & Jackson, ; Walsh, Bailey, Childs, Nicol, & Bonson, ; Walsh, Nicol, & Childs, ; Walsh & Watterson, ). This research has taught us that (a) normal fault systems are fundamentally and universally segmented (e.g.…”

Extensional fault and fold growth: Impact on accommodation evolution and sedimentary infill

“…Jackson & Rotevatn, ; Figure b). Following validation criteria outlined in Jackson et al (), however, uncertainties with respect to whether the hangingwall basin was underfilled and the footwall high eroded during rifting leave these conclusions speculative.…”

“…Lithologic descriptions were based on Cutbill & Challinor, 1965;Ezaki et al, 1994;Gjelberg & Steel, 1981;Glørstad-Clark et al, 2010;Marin, Escalona, Sliwihska, Nøhr-Hansen, & Mordasova, 2017;Mørk & Elvebakk, 1999;0000, in press;Norwegian Petroleum Directorate FactPages, 2014;Steel & Worsley, 1984;Smelror, Mørk, Monteil, Rutledge, & Leereveld, 1998;Worsley et al, 2001 Figure 6) and throw-length (T-X) plots (Figure 7), applying the methods outlined in Tvedt, Rotevatn, Jackson, Fossen, and Gawthorpe (2013) and accounting for near-fault deformation by projecting the interpreted horizons onto the fault based on the regional dip (see also Baudon & Cartwright, 2008;Childs, Nicol, Walsh, & Watterson, 2002;Dawers & Anders, 1995;Gawthorpe & Leeder, 2000;Mansfield & Cartwright, 1996; Rotevatn, Jackson, Tvedt, Bell, & Blaekkan, 2018a; Thorsen, 1963;Walsh & Watterson, 1990). We note uncertainties related to these methods such as burial compaction, thickness differences driven by nontectonic processes, erosion of footwall highs and underfilled basins as outlined in Jackson, Bell, Rotevatn, and Tvedt (2017). For simplicity, the basin fill has been divided into stratal units (SU1-SU9) based on the architecture of reflector packages (Figures 2c and 3).…”

A parametric fault displacement model to introduce kinematic control into modeling faults from sparse data

“…Syn-faulting (or growth) layers are thicker on the hanging wall compared to the footwall across normal faults (Figure 7.a). The thickness difference is quantified by the expansion index (EI, Figure 7.b) defined as the ratio between hanging wall (HW thickness ) and footwall (F W thickness ) thicknesses (Fossen, 2016;Tvedt et al, 2016;Jackson et al, 2017):…”